TY - JOUR

T1 - Criterion validity and reliability of a smartphone delivered sub-maximal fitness test for people with type 2 diabetes

AU - Brinklov, Cecilie Fau

AU - Thorsen, Ida Kær

AU - Karstoft, Kristian

AU - Brøns, Charlotte

AU - Valentiner, Laura

AU - Langberg, Henning

AU - Vaag, Allan Arthur

AU - Nielsen, Jens Steen

AU - Pedersen, Bente Klarlund

AU - Ried-Larsen, Mathias

PY - 2016/10/7

Y1 - 2016/10/7

N2 - Background: Prevention of multi-morbidities following non-communicable diseases requires a systematic registration of adverse modifiable risk factors, including low physical fitness. The aim of the study was to establish criterion validity and reliability of a smartphone app (InterWalk) delivered fitness test in patients with type 2 diabetes.Methods: Patients with type 2 diabetes (N = 27, mean (SD) age 64.2 (5.9) years, BMI 30.0 (5.1) kg/m2, (30 % male)) completed a 7-min progressive walking protocol twice (with and without encouragement). VO2 during the test was assessed using indirect calorimetry and the acceleration (vector magnitude) from the smartphone was obtained. The vector magnitude was used to predict VO2peak along with the co-variates weight, height and sex. The validity of the algorithm was tested when the smartphone was placed in the right pocket of the pants or jacket. The algorithm was validated using leave-one-out cross validation. Test-retest reliability was tested in a subset of participants (N = 10).Results: The overall VO2peak prediction of the algorithm (R2) was 0.60 and 0.45 when the smartphone was placed in the pockets of the pants and jacket, respectively (p < 0.001). The mean bias (limits of agreement) in the cross validation was−0.4 (38) % (pants) and−0.1 (46) % (jacket). When the smartphone was placed in the jacket a significant intensity dependent bias (r = 0.5, p = 0.02) was observed. The test-retest intraclass correlations were 0.85 and 0.86 (p < 0.001), for the pants and jacket, respectively. No effects of encouragement were observed on test performance.Conclusion: In conclusion, the InterWalk Fitness Test is accurate and reliable for persons with type 2 diabetes when the smartphone is placed in the side pocket of the pants for. The test could give a fair estimate of the CRF in absence of a progressive maximal test during standardized conditions with the appropriate equipment.Trial registration: www.clinicaltrials.org (NCT02089477), first registered (prospectively) on March 14th 2014

AB - Background: Prevention of multi-morbidities following non-communicable diseases requires a systematic registration of adverse modifiable risk factors, including low physical fitness. The aim of the study was to establish criterion validity and reliability of a smartphone app (InterWalk) delivered fitness test in patients with type 2 diabetes.Methods: Patients with type 2 diabetes (N = 27, mean (SD) age 64.2 (5.9) years, BMI 30.0 (5.1) kg/m2, (30 % male)) completed a 7-min progressive walking protocol twice (with and without encouragement). VO2 during the test was assessed using indirect calorimetry and the acceleration (vector magnitude) from the smartphone was obtained. The vector magnitude was used to predict VO2peak along with the co-variates weight, height and sex. The validity of the algorithm was tested when the smartphone was placed in the right pocket of the pants or jacket. The algorithm was validated using leave-one-out cross validation. Test-retest reliability was tested in a subset of participants (N = 10).Results: The overall VO2peak prediction of the algorithm (R2) was 0.60 and 0.45 when the smartphone was placed in the pockets of the pants and jacket, respectively (p < 0.001). The mean bias (limits of agreement) in the cross validation was−0.4 (38) % (pants) and−0.1 (46) % (jacket). When the smartphone was placed in the jacket a significant intensity dependent bias (r = 0.5, p = 0.02) was observed. The test-retest intraclass correlations were 0.85 and 0.86 (p < 0.001), for the pants and jacket, respectively. No effects of encouragement were observed on test performance.Conclusion: In conclusion, the InterWalk Fitness Test is accurate and reliable for persons with type 2 diabetes when the smartphone is placed in the side pocket of the pants for. The test could give a fair estimate of the CRF in absence of a progressive maximal test during standardized conditions with the appropriate equipment.Trial registration: www.clinicaltrials.org (NCT02089477), first registered (prospectively) on March 14th 2014

KW - Fitness

KW - Smartphone

KW - Validity

KW - Reliability

KW - Type 2 diabetes mellitus

KW - Exercise

U2 - 10.1186/s13102-016-0056-7

DO - 10.1186/s13102-016-0056-7

M3 - Journal article

C2 - 28174664

VL - 8

JO - BMC Sports Science, Medicine and Rehabilitation

JF - BMC Sports Science, Medicine and Rehabilitation

SN - 2052-1847

M1 - 31

ER -